May 13, 2017

The details of how massive stars explode remains one of the biggest questions in astrophysics. Located in the neighboring galaxy of the Small Magellanic Cloud, this supernova, SNR B0049-73.6, provides astronomers with another excellent example of such an explosion to study. Chandra observations of the dynamics and composition of the debris from the explosion support the view that the explosion was produced by the collapse of the central core of a star. In this image, X-rays from Chandra (purple) are combined with infrared data from the 2MASS survey (red, green, and blue).

This image covers a field of 0.5° x 0.5° in the Southern constellation of Norma (The Level) and in the direction of the "Great Attractor". This region is at an angular distance of about 7° from the main plane of the Milky Way, i.e. less than 15 times the width of the image shown. In this colour composite, the foreground stars in the Milky Way mostly appear as whitish spots (the "crosses" around some of the brighter stars are caused by reflections in the telescope optics). Many background galaxies are also seen. They form a huge cluster (ACO 3627) with a number of bright galaxies near the center — they stand out by their larger size and yellowish colour. In order to facilitate transport over the Web, this image has been compressed by a factor of four from its original size (8500 x 8250 pixels).

Five exposures each were made in blue (B-band filter; 5 x 300 sec), red (R-band filter; 5 x 180 sec) and near-infrared (narrow-band filter centered at 816 nm; 5 x 240 sec) light and combined into a false-colour composite by using blue, green, and red colour for the three images, respectively. A logarithmic intensity scale is used to better show the inner as well as the outer regions of the galaxies in this field.

May 12, 2017

Infant stars are glowing gloriously in this infrared image of the Serpens star-forming region, captured by NASA's Spitzer Space Telescope.

The reddish-pink dots are baby stars deeply embedded in the cosmic cloud of gas and dust that collapsed to create it. A dusty disk of cosmic debris, or "protoplanetary disk," that may eventually form planets, surrounds the infant stars.

Wisps of green throughout the image indicate the presence of carbon rich molecules called polycyclic aromatic hydrocarbons. On Earth, these molecules can be found on charred barbecue grills and in automobile exhaust. Blue specks sprinkled throughout the image are background stars in our Milky Way galaxy.

The Serpens star-forming region is located approximately 848 light-years away in the Serpens constellation.

The image is a three-channel, false-color composite, where emission at 4.5 microns is blue, emission at 8.0 microns is green, and 24 micron emission is red.

This is a NASA/ESA Hubble Space Telescope image of the galaxy cluster MACS J0152.5-2852. Shown in blue on the image is a map of the dark matter found within the cluster. This cluster was part of a study of 72 galaxy cluster collisions which determined that dark matter interacts with other dark matter even less than previously thought.

NGC 6946 is a medium-sized, face-on spiral galaxy about 22 million light years away from Earth. In the past century, eight supernovas have been observed to explode in the arms of this galaxy. Chandra observations (purple) have, in fact, revealed three of the oldest supernovas ever detected in X-rays, giving more credence to its nickname of the "Fireworks Galaxy." This composite image also includes optical data from the Gemini Observatory in red, yellow, and cyan.

Using data from Chandra and other telescopes, astronomers have found a possible "recoiling" black hole. This black hole, which contains about 160 million solar masses, may have formed and then been set in motion by the collision of two smaller black holes (depicted in the artist's illustration). Astronomers found this candidate recoiling black hole after sifting through data of thousands of galaxies. Such moving supermassive black holes are interesting because they may reveal more about the rate and direction of spin for these enigmatic objects before they merge.

Supermassive black holes are typically stationary objects located at the centers of most galaxies.

Under some circumstances, these black holes that contain millions or even billions of times the mass of the Sun can be set in motion.

After searching through Chandra's X-ray and optical data, astronomers found a new candidate of such a "recoiling" black hole.

This recoiling black hole candidate is located in an elliptical galaxy about 3.9 billion light years from Earth.

Supermassive holes are generally stationary objects, sitting at the centers of most galaxies. However, using data from NASA's Chandra X-ray Observatory and other telescopes, astronomers recently hunted down what could be a supermassive black hole that may be on the move.

This possible renegade black hole, which contains about 160 million times the mass of our Sun, is located in an elliptical galaxy about 3.9 billion light years from Earth. Astronomers are interested in these moving supermassive black holes because they may reveal more about the properties of these enigmatic objects.

The left image is from the Hubble data, which shows two bright points near the middle of the galaxy. One of them is located at the center of the galaxy and the other is located about 3,000 light years away from the center. The latter source shows the properties of a growing supermassive black hole and its position matches that of a bright X-ray source detected with Chandra (right image). Using data from the SDSS and the Keck telescope in Hawaii, the team determined that the growing black hole located near, but visibly offset from, the center of the galaxy has a velocity that is different from the galaxy. These properties suggest that this source may be a recoiling supermassive black hole.

This black hole may have "recoiled," in the terminology used by scientists, when two smaller supermassive black holes collided and merged to form an even larger one. At the same time, this collision would have generated gravitational waves that emitted more strongly in one direction than others. This newly formed black hole could have received a kick in the opposite direction of those stronger gravitational waves. This kick would have pushed the black hole out of the galaxy's center, as depicted in the artist's illustration.

The strength of the kick depends on the rate and direction of spin of the two smaller black holes before they merge. Therefore, information about these important but elusive properties can be obtained by studying the speed of recoiling black holes.

Astronomers found this recoiling black hole candidate by sifting through X-ray and optical data for thousands of galaxies. First, they used Chandra observations to select galaxies that contain a bright X-ray source and were observed as part of the Sloan Digital Sky Survey (SDSS). Bright X-ray emission is a common feature of supermassive black holes that are rapidly growing.

Next, the researchers looked to see if Hubble Space Telescope observations of these X-ray bright galaxies revealed two peaks near their center in the optical image. These two peaks might show that a pair of supermassive black holes is present or that a recoiling black hole has moved away from the cluster of stars in the center of the galaxy.

If those criteria were met, then the astronomers examined the SDSS spectra, which show how the amount of optical light varies with wavelength. If the researchers found telltale signatures in the spectra indicative of the presence of a supermassive black hole, they followed up with an even closer examination of those galaxies.

After all of this searching, a good candidate for a recoiling black hole was discovered. The left image in the inset is from the Hubble data, which shows two bright points near the middle of the galaxy. One of them is located at the center of the galaxy and the other is located about 3,000 light years away from the center. The latter source shows the properties of a growing supermassive black hole and its position matches that of a bright X-ray source detected with Chandra (right image in inset). Using data from the SDSS and the Keck telescope in Hawaii, the team determined that the growing black hole located near, but visibly offset from, the center of the galaxy has a velocity that is different from the galaxy. These properties suggest that this source may be a recoiling supermassive black hole.

The host galaxy of the possible recoiling black hole also shows some evidence of disturbance in its outer regions, which is an indication that a merger between two galaxies occurred in the relatively recent past. Since supermassive black hole mergers are thought to occur when their host galaxies merge, this information supports the idea of a recoiling black hole in the system.

Moreover, stars are forming at a high rate in the galaxy, at several hundred times the mass of the Sun per year. This agrees with computer simulations, which predict that star formation rates may be enhanced for merging galaxies particularly those containing recoiling black holes.

Another possible explanation for the data is that two supermassive black holes are located in the center of the galaxy but one of them is not producing detectable radiation because it is growing too slowly. The researchers favor the recoiling black hole explanation, but more data are needed to strengthen their case.

May 11, 2017

3C 397 (also known as G41.1-0.3) is a Galactic supernova remnant with an unusual shape. Researchers think its box-like appearance is produced as the heated remains of the exploded star -- detected by Chandra in X-rays (purple) -- runs into cooler gas surrounding it. This composite of the area around 3C 397 also contains infrared emission from Spitzer (yellow) and optical data from the Digitized Sky Survey (red, green, and blue).

In the summer of the year 1054 AD, Chinese astronomers saw a new "guest star," that appeared six times brighter than Venus. So bright in fact, it could be seen during the daytime for several months.

This "guest star" was forgotten about until 700 years later with the advent of telescopes. Astronomers saw a tentacle-like nebula in the place of the vanished star and called it the Crab Nebula. Today we know it as the expanding gaseous remnant from a star that self-detonated as a supernova, briefly shining as brightly as 400 million suns. The explosion took place 6,500 light-years away. If the blast had instead happened 50 light-years away it would have irradiated Earth, wiping out most life forms.

In the late 1960s astronomers discovered the crushed heart of the doomed star, an ultra-dense neutron star that is a dynamo of intense magnetic field and radiation energizing the nebula. Astronomers therefore need to study the Crab Nebula across a broad range of electromagnetic radiation, from X-rays to radio waves.

This image combines data from five different telescopes: the VLA (radio) in red; Spitzer Space Telescope (infrared) in yellow; Hubble Space Telescope (visible) in green; XMM-Newton (ultraviolet) in blue; and Chandra X-ray Observatory (X-ray) in purple.

May 10, 2017

Sunset Crater is a cinder cone located north of Flagstaff in U.S. State of Arizona. The crater is within the Sunset Crater Volcano National Monument.

Sunset Crater is the youngest in a string of volcanoes (the San Francisco volcanic field) that is related to the nearby San Francisco Peaks.

The date of the eruptions that formed the 340-meter-high cone (1,120 ft) was initially derived from tree-ring dates, suggesting the eruption began between the growing seasons of A.D. 1064–1065. However, more recent geologic and archaeological evidence places the eruption around A.D. 1085. The largest vent of the eruption, Sunset Crater itself, was the source of the Bonito and Kana-a lava flows that extended about 2.5 kilometers (1.6 mi) NW and 9.6 kilometers (6 mi) NE, respectively. Additional vents along a 10-kilometer-long fissure (6.2 mi) extending SE produced small spatter ramparts and a 6.4-kilometer-long lava flow (4 mi) to the east. The Sunset Crater eruption produced a blanket of ash and lapilli covering an area of more than 2,100 square kilometers (810 sq mi) and forced the temporary abandonment of settlements of the local Sinagua people. The volcano has partially revegetated, with pines and wildflowers. The crater is the namesake for the Sunset Crater Beardtongue (Penstemon clutei). Since the last eruption of the volcano is a recent occurrence, it is considered dormant by volcanologists.

Damage from hikers forced the National Park Service to close a trail leading to the crater, but a short trail at the base remains.

The hiking trail below the summit skirts the substantial Bonito Lava Flow. This hardened lava is black and appears fresh as it has devastated the forest in its path. The lava flow also created an ice cave or tube that is now closed to the public after a partial collapse.

This image of Centaurus A shows a spectacular new view of a supermassive black hole's power. Jets and lobes powered by the central black hole in this nearby galaxy are shown by submillimeter data (colored orange) from the Atacama Pathfinder Experiment (APEX) telescope in Chile and X-ray data (colored blue) from the Chandra X-ray Observatory. Visible light data from the Wide Field Imager on the Max-Planck/ESO 2.2 m telescope, also located in Chile, shows the dust lane in the galaxy and background stars. The X-ray jet in the upper left extends for about 13,000 light years away from the black hole. The APEX data shows that material in the jet is travelling at about half the speed of light.

When radiation and winds from massive young stars impact clouds of cool gas, they can trigger new generations of stars to form. This is what may be happening in this object known as the Elephant Trunk Nebula (or its official name of IC 1396A). X-rays from Chandra (purple) have been combined with optical (red, green, and blue) and infrared (orange and cyan) to give a more complete picture of this source.

May 9, 2017

This image provides a view into the central region of a galaxy that is similar in overall appearance to our own Milky Way, but contains a much more active supermassive black hole within the white area near the top. This galaxy, known as NGC 4945, is only about 13 million light years from Earth and is seen edge-on. X-rays from Chandra (blue), which have been overlaid on an optical image from the European Space Observatory, reveal the presence of the supermassive black hole at the center of this galaxy.

Saturn's hexagonal polar jet stream is the shining feature of almost every view of the north polar region of Saturn. The region, in shadow for the first part of the Cassini mission, now enjoys full sunlight, which enables Cassini scientists to directly image it in reflected light.

Although the sunlight falling on the north pole of Saturn is enough to allow us to image and study the region, it does not provide much warmth. In addition to being low in the sky (just like summer at Earth's poles), the sun is nearly ten times as distant from Saturn as from Earth. This results in the sunlight being only about 1 percent as intense as at our planet.

This view looks toward Saturn from about 31 degrees above the ring plane. The image was taken with the Cassini spacecraft wide-angle camera on Jan. 22, 2017 using a spectral filter which preferentially admits wavelengths of near-infrared light centered at 939 nanometers.

The view was obtained at a distance of approximately 560,000 miles (900,000 kilometers) from Saturn. Image scale is 33 miles (54 kilometers) per pixel.

May 7, 2017

G266.2-1.2 was produced by the explosion of a massive star in the Milky Way galaxy. A Chandra observation of this supernova remnant reveals the presence of extremely high-energy particles produced as the shock wave from this explosion expands into interstellar space. In this image, the X-rays from Chandra (purple) have been combined with optical data from the Digitized Sky Survey (red, green, and blue).

This enhanced color view of Jupiter's south pole was created by citizen scientist Gabriel Fiset using data from the JunoCam instrument on NASA's Juno spacecraft. Oval storms dot the cloudscape. Approaching the pole, the organized turbulence of Jupiter's belts and zones transitions into clusters of unorganized filamentary structures, streams of air that resemble giant tangled strings.

The image was taken on December 11, 2016 at 9:44 a.m. PST (12:44 p.m. EST), from an altitude of about 32,400 miles (52,200 kilometers) above the planet's beautiful cloud tops.